Light-weight composites are commonly used in manufacturing cars with lighter weight and improved fuel economy. The composites are currently produced using expensive steel tools and technologically advanced compression molding machines.
Open tool molding is a process for producing relatively low cost composite panels at low volumes. While steel molds are often used for other molding operations, the open tool molding process was developed to use less expensive one-sided epoxy or polyester molds to produce various products, such as composite panels with an in-mold finish. To obtain a reasonable surface appearance, the process requires the use of a gel coat over a supporting composite laminate. In the process, a mold surface is first cleaned, a mold release coating is optionally applied, and a layer of a gel coat is applied and partially cured. A laminate is then applied to the gel coat layer, and the laminate and gel coat are cured to form a unitary part having a surface defined by the cured gel coat. Molded parts can be produced by this method to have a finish bearing any desired color originally carried by the gel coat. However, attainment of a gel coat surface with a suitably smooth finish remains a challenge.
It is desirable to produce a pigmented gel coat, so as to eliminate the need of painting, and to provide good protection against fading due to heat and ultraviolet radiation. A particular challenge is to produce a surface finish on the gel coat that is both defect free and highly resistant to degradation from exposure to ultraviolet radiation.
Therefore, it is desirable to improve the surface appearance of the gel coat, and provide a part that will maintain color and high gloss when exposed to the elements.